Hearing devices, such as hearing aids, are usually placed within housings comprising of at least two shells. The shells are connected to each other to form the assembled, closed housing of the hearing device.
Screws are commonly used for the connection of such shells. If the shells are made of plastic, so called self-cutting screws may be used. Such self-cutting screws do not need to be inserted into threads, in contrary to regular screws, but only need a bore with a smaller diameter than the diameter of the screw thread. Cutting surfaces are provided at the coin point of such a screw for cutting themselves into the bore and thus producing themselves a thread.
Regular screws engaging into nuts may alternatively be used, said nuts being provided within receiving openings at the inside of the shells.
For both known solutions described above, the screw head is visible from the outside of the housing because the screw has to be operated from the outside. Thus, those solutions are unconvincing and the respective openings for the screws at the outside of the housing are subject to contamination.
Alternative housings are known with shells that are connected via pins with a smooth surface. Such housings are separated parallel with respect to the axis of the pins in contrary to housings with screws that are separated transversally with respect to the axis of the screws. The design of the shells are therefore more complex involving more expensive injection molding tools in contrary to common shells for screws. That arises from the characteristic of the pins to be stressed only transversally to its longitudinal axis. Thus, eyelets have to be provided at the shell for receiving the pins that rises the complexity of the injection molding tools. Furthermore, the pin heads are visible from the outside and the respective receiving bores tend to collect dirt even though they are smaller in diameter with respect to the bores used for screws.
Further solutions are known with shells that interconnect via resilient tongues with hooks. The hooks of said tongues interlock with engaging means arranged at the shell after assembling of the shells. The respective injection molding tools to form such means are as well complex and therefore expensive. Furthermore, such connections are usually not very stable or robust. The hooks, tongues and/or engaging means will often be damaged when opening the housing or already by closing the shells of the housing. A further disadvantage lies in the fact that such connecting means usually require a lot of space that has a negative impact onto the dimension of the housing which is usually required to be highly miniaturized.